It is well known to provide a tailgate which is hingedly mounted to a truck body for pivotal movement about a hinge axis between an open horizontal position and a closed vertical position. It is common to provide detachable folding straps to support the tailgate in the open position.
It is also well known for the tailgate to be removable from the truck body when the tailgate is pivoted to a partially open tailgate removal position. Typically, the tailgate may include hinge pins extending outwardly along the hinge axis which are shaped to removably connect into cup-shaped trunnions carried by the truck body. When the tailgate is pivoted to the tailgate removal position, one of the hinge pins is positioned for removal through a slot in its connecting trunnion when the tailgate is lifted from the truck body.
It is well known for the hinge pins to be freely rotatable within the trunnions, such that the weight of the tailgate is raised and lowered manually by the operator when the tailgate is moved between the open and closed positions.
Since trucks are now commonly being used by a wide variety of operators, it would be desirable to provide counterbalance effort to assist with the opening and closing of tailgate and yet still permit removal of the tailgate from the truck body. The prior art discloses counterbalance mechanisms, such as springs, struts and torsion bars, for use with tailgates; however, these mechanisms do not permit removal of the tailgate.
The prior art also discloses a removable tailgate having a pinion in place of a hinge pin. The pinion matably engages with a counterbalance spring comprised of a spring-loaded rack assembled inside the truck body to provide a counterbalance effort. However, this rack and pinion arrangement has the shortcoming that the operator must match up the rack and pinion gears while assembling the tailgate to the truck body and that the counterbalance spring is not subassembled with the tailgate and is not removable with the tailgate from the vehicle body.
Thus, it would be desirable to provide an improved counterbalance mechanism for a removable tailgate which assists with the opening and closing of the tailgate, allows for subassembly of the counterbalance spring with the tailgate and permits facile removal of the tailgate and counterbalance spring from the vehicle body.